Thanks, PA.

I could not find coolant drain plug on parts list.
I will be able to drain as instructed next time.

I could not find how to drain coolant fluid on service manual.
So, I removed fluid with injector. Some fluid remained.
I had set up a resin sheet and a bottle as shown attached photo.
I tried to replaced with thermostat not to leak fluid.
I made it. There was not fluid leaking.

By the way,
I have ...

PA wrote:You can bypass the thermostat by joining the two terminals. This would make the fan run all the time which you may not want when it's cold.

I saw Someone's Techno on Youtube bypassed fan. The fan runs all the time when ride.
Thanks everyone.

I have got another problem in cooling system.
I started engine and several minutes later,
boiling noise came from radiator. But coolant fan did not work.
I thought thermostat wrong.
I removed wire harness from thermostat and I connect it to car battery.
The coolant fan work properly. It turned out ...

Loose kickstart lever hit frame,so I put longer bolt with nut as shown attached. I hope it will work not to hit frame.

As I replaced leaking fuel cock with new one,I tried to kick start again.
Unfortunately loose arm hit the frame and frame was damaged as shown attached photo.
I know best way buying REV3's kickstart lever.
And I am thinking another way to fix.

I could remove sprocket with bearing puller. So I installed chain slide block.

Front sprocket has to be removed when replacing chain slide block.
I tried to remove sprocket but could not.
Sprocket stuck on spline stiff. I am going to find good way to remove sprocket.
Then,I have decided to buy a 3jaws bearing puller to remove sprocket.

I am replacing broken block with new one.
I took a picture of old and new block as shown on attached.
Pre-owner seemed to give up replace wasted parts.

As I finished installation of new clutch system,I filled mixed gasoline to Beta.
But gasoline leaked at on position. I will replace with new petcock for Techno.